Amicus Curiae Brief — Suncor Energy (U.S.A.) Inc., et al., Petitioners v. County Commissioners of Boulder County, et al.

No. 25-170

In the

Supreme Court of the United States

______________

SUNCOR ENERGY (U.S.A.) INC., ET AL.,

Petitioners,

v.

COUNTY COMMISSIONERS OF BOULDER COUNTY;

CITY OF BOULDER,

Respondents.

______________

On Petition for a Writ of Certiorari to the

Supreme Court of Colorado

______________

BRIEF OF HOUSE MAJORITY LEADER STEVE

SCALISE AND 102 OTHER MEMBERS OF

CONGRESS AS AMICI CURIAE IN SUPPORT OF

PETITIONERS

______________

MICHAEL BUSCHBACHER

JARED M. KELSON

Counsel of Record

JENNIFER K. HARDY

LAURA B. RUPPALT

BOYDEN GRAY PLLC

800 Connecticut Ave NW,

Suite 900

Washington, DC 20006

(202) 955-0620

jkelson@boydengray.com

i

QUESTION PRESENTED

Whether federal law precludes state-law claims

seeking relief for injuries allegedly caused by the

effects of interstate and international greenhouse-gas

emissions on the global climate.

ii

TABLE OF CONTENTS

INTEREST OF AMICI CURIAE ............................... 1

SUMMARY OF ARGUMENT .................................... 4

ARGUMENT ............................................................... 6

I.

THIS CASE IS CRITICAL TO THE NATION.............. 6

A.

Energy Is Fundamentally Important ....... 6

B.

State and Local Governments Are

Trying to Usurp Federal Authority ........... 8

II. THIS CASE IS STRAIGHTFORWARD ..................... 11

A.

Interstate and International Emissions

Are the Domain of Federal Law .............. 11

B.

Congress Did Not Authorize States to

Regulate Interstate and International

Emissions in the Clean Air Act ............... 14

C.

Confirming Federal Authority Over

Interstate and International Emissions

Respects States......................................... 16

III. FURTHER PERCOLATION IS UNNECESSARY ....... 17

CONCLUSION ......................................................... 21

iii

TABLE OF AUTHORITIES

CASES

Page(s)

Am. Elec. Power Co. v. Connecticut,

564 U.S. 410 (2011) .................................... 5, 13, 15

Am. Ins. Ass’n v. Garamendi,

539 U.S. 396 (2003) .............................................. 14

Banco Nacional de Cuba v. Sabbatino,

376 U.S. 398 (1964) .............................................. 13

BMW of N. Am., Inc. v. Gore,

517 U.S. 559 (1996) .............................................. 17

City & County of Honolulu v. Sunoco LP,

537 P.3d 1173 (Haw. 2023) .................................. 17

City of Milwaukee v. Illinois,

451 U.S. 304 (1981) .............................................. 13

City of New York v. Chevron Corp.,

993 F.3d 81 (2d Cir. 2021).......................... 5, 12, 17

North Carolina v. Tenn. Valley Auth.,

615 F.3d 291 (2010) .............................................. 17

Franchise Tax Bd. of Cal. v. Hyatt,

587 U.S. 230 (2019) .............................................. 17

Fuld v. Palestine Liberation Org.,

606 U.S. 1 (2025) .................................................. 14

Georgia v. Tenn. Copper Co.,

206 U.S. 230 (1907) .............................................. 12

iv

Gregory v. Ashcroft,

501 U.S. 452 (1991) .............................................. 14

Illinois v. City of Milwaukee,

406 U.S. 91 (1972) .......................................... 12, 13

Illinois v. City of Milwaukee,

731 F.2d 403 (7th Cir. 1984) ................................ 17

Int’l Paper Co. v. Ouellette,

479 U.S. 481 (1987) ........................................ 13, 16

Kansas v. Colorado,

206 U.S. 46 (1907) ................................................ 17

Kurns v. R.R. Friction Prods. Corp.,

565 U.S. 625 (2012) ................................................ 9

Minnesota v. Am. Petroleum Inst.,

63 F.4th 703 (8th Cir. 2023) ................................ 11

Native Vill. of Kivalina v. ExxonMobil

Corp., 696 F.3d 849 (9th Cir. 2012) ..................... 16

S.D. Building Trades Council v.

Garmon, 359 U.S. 236 (1959)................................. 9

Texas v. Pankey,

441 F.2d 236 (10th Cir. 1971) .............................. 12

U.S. Forest Serv. v. Cowpasture River

Pres. Ass’n, 590 U.S. 604 (2020) ...................... 5, 14

United States v. Locke,

529 U.S. 89 (2000) ................................................ 16

v

Whitman v. Am. Trucking Ass’ns,

531 U.S. 457 (2001) .......................................... 5, 15

STATUTES

42 U.S.C. § 15927(b)(1) ................................................ 7

Pub. L. No. 119-21, 139 Stat. 72 (2025) ...................... 7

EXECUTIVE ORDERS

Declaring a National Energy Emergency,

Exec. Order No. 14156,

90 Fed. Reg. 8433 (Jan. 29, 2025)...................... 7, 8

Establishing the National Energy Dominance

Council, Exec. Order No. 14213,

90 Fed. Reg. 9945 (Feb. 20, 2025).......................... 8

Protecting American Energy from State

Overreach, Exec. Order No. 14260,

90 Fed. Reg. 15513 (Apr. 14, 2025)........................ 8

Strengthening the Reliability and Security of

the United States Electric Grid,

Exec. Order No. 14262,

90 Fed. Reg. 15521 (Apr. 14, 2025)........................ 8

Unleashing American Energy,

Exec. Order No. 14154,

90 Fed. Reg. 8353 (Jan. 29, 2025).......................... 8

vi

OTHER AUTHORITIES

Daniel Dassow, U.S. Energy Secretary, OpenAI

Co-founder Say AI Race Is ‘Manhattan

Project 2’ In Oak Ridge Visit, Knoxville

News Sentinel (Feb. 28, 2025) ............................... 7

David Arkush & Donald Braman, Climate

Homicide: Prosecuting Big Oil for Climate

Deaths, 48 Harv. Env’t L. Rev. 45 (2024) ............ 19

IPCC, Climate Change 2022: Mitigation of

Climate Change, Working Group III

Contribution to the Sixth Assessment

Report of the Intergovernmental Panel on

Climate Change (2022) ......................................... 11

U.S. Dep’t of Energy, Comprehensive Annual

Energy Data: Total Site-Delivered Energy

Use in All End-Use Sectors, by Federal

Agency (Billion Btu) (visited Oct. 9, 2025) ............ 6

U.S. Energy Info. Admin., Frequently Asked

Questions (FAQs): How Much Oil Is

Consumed in the United States?

(updated Oct. 9, 2024) ............................................ 6

1

INTEREST OF AMICI CURIAE1

Amici curiae are 103 duly elected Members of

Congress. Amici sit on various committees with

jurisdiction over matters of energy, natural resources,

and the environment. Amici have a profound and

direct interest in preserving the authority vested in

the federal government by the Constitution over

interstate

and

international

greenhouse-gas

emissions, including the fundamental power of

Congress to regulate pursuant to the Commerce

Clause.

The decision below supplants the legislative

prerogative of Congress, permitting a balkanized

patchwork of state and local regulation over matters

of uniquely federal concern. Amici file this brief to

defend their role in setting energy policy for the

United States—including the regulation of interstate

and international emissions—and to prevent state

and local governments from undermining the

comprehensive statutory schemes that Congress has

enacted.

The following is the full list of amici:

1 Counsel for amici curiae timely provided notice to all parties of

intent to file this brief. No party’s counsel authored this brief in

whole or in part, and no person or entity other than amici or their

counsel made a monetary contribution intended to fund its

preparation or submission.

2

House of Representatives

Steve Scalise

Brett Guthrie

Bruce Westerman

Robert B. Aderholt

Mark Alford

Jodey C. Arrington

Brian Babin

Troy Balderson

Andy Barr

Aaron Bean

Cliff Bentz

Stephanie Bice

Sheri Biggs

Gus M. Bilirakis

Lauren Boebert

Mike Bost

Vern Buchanan

Ken Calvert

Kat Cammack

Mike Carey

Buddy Carter

Ben Cline

Michael Cloud

Andrew Clyde

Jeff Crank

Warren Davidson

Chuck Edwards

Ron Estes

Gabe Evans

Julie Fedorchak

Randy Fine

Brad Finstad

Scott Fitzgerald

Chuck Fleischmann

Vince Fong

Virginia Foxx

Scott Franklin

Craig Goldman

Tony Gonzales

Lance Gooden

Paul A. Gosar, D.D.S.

Sam Graves

Marjorie Taylor Greene

H. Morgan Griffith

Harriet M. Hageman

Abraham Hamadeh

Mike Haridopolos

Pat Harrigan

Diana Harshbarger

Kevin Hern

Clay Higgins

French Hill

Erin Houchin

Richard Hudson

Bill Huizenga

Jeff Hurd

Ronny L. Jackson

Mike Kennedy

Doug LaMalfa

Nick Langworthy

Julia Letlow

3

Nicole Malliotakis

Tracey Mann

Michael McCaul

Rich McCormick

Addison McDowell

John McGuire

Mark Messmer

Carol D. Miller

Cory Mills

Barry Moore

Riley Moore

Tim Moore

Gregory F. Murphy,

M.D.

Troy E. Nehls

Dan Newhouse

Bob Onder

Burgess Owens

Gary Palmer

Jimmy Patronis

Scott Perry

August Pfluger

Mike D. Rogers

John Rose

David Rouzer

Michael Rulli

John Rutherford

Derek Schmidt

Pete Sessions

Jefferson Shreve

Adrian Smith

Jason Smith

Pete Stauber

Dale Strong

Claudia Tenney

Glenn GT Thompson

Beth Van Duyne

Ann Wagner

Tim Walberg

Daniel Webster

Roger Williams

Rudy Yakym

Ryan Zinke

4

SUMMARY OF ARGUMENT

In recent years, multiple state and local

governments have launched a courtroom war against

the American energy industry. Unhappy with

national energy policy that—in their view—has not

moved quickly enough to replace fossil fuels, they

attempt to wield state law and state court judgments

to pursue crushing penalties against American oil and

gas companies for harms allegedly caused by global

greenhouse-gas emissions on the global climate. In so

doing, these States and localities would dictate

national energy policy themselves. This approach

upends the constitutional balance between federal

and state authority, discards a century of this Court’s

precedent, and undermines the federal legislative

process. It must stop now.

Abundant and reliable energy is fundamental to

our national stability, prosperity, and security. Both

Congress and the President are unified in prioritizing

that reality for all Americans. But Respondents, the

City and County of Boulder, Colorado, would

substitute their own preferred policies for those of the

federal government. They dress their complaint in the

language of state law, but they cannot escape that

every claim in some way turns on global greenhousegas emissions. And the sheer magnitude of the

damages at issue—likely tens of billions of dollars—

would restructure the American energy industry if not

bankrupt it altogether, especially when multiplied by

the dozens of similar cases around the country.

This has continued long enough. States have no

authority to regulate interstate and international

emissions that originate beyond their respective

5

borders. This Court has reiterated time and again

that “the basic scheme of the Constitution …

demands” the application of federal law to “‘air and

water in their ambient or interstate aspects.’” Am.

Elec. Power Co. (“AEP”) v. Connecticut, 564 U.S. 410,

421 (2011) (quoting Illinois v. City of Milwaukee

(“Milwaukee I”), 406 U.S. 91, 103 (1972)). That is why

“[f]or over a century, a mostly unbroken string of cases

has applied federal law to disputes involving

interstate air or water pollution.” City of New York v.

Chevron Corp., 993 F.3d 81, 91 (2d Cir. 2021)

(collecting cases).

Congress passed the Clean Air Act against this

backdrop. This Court has emphasized that Congress

must “enact exceedingly clear language if it wishes to

significantly alter the balance between federal and

state power.” U.S. Forest Serv. v. Cowpasture River

Pres. Ass’n, 590 U.S. 604, 621–22 (2020) (emphasis

added). The Clean Air Act contains no indication—

much less an “exceedingly clear” one—that Congress

intended to disturb the existing line between federal

and state authority to regulate interstate and

international emissions. Put another way, Congress

“does not … hide elephants in mouseholes” and subtly

empower state law and state courts to pursue

crippling damages against an essential industry for

worldwide conduct, especially for claims within the

exclusive domain of federal law. Whitman v. Am.

Trucking Ass’ns, 531 U.S. 457, 468 (2001).

The issues in this case have been developed at

length, and the disruption to the country grows daily.

This Court should not stand by while Respondents use

6

their state law and state courts to supplant federal

authority and set national energy policy.

The Court should grant the petition for certiorari

and reverse.

ARGUMENT

I.

THIS CASE IS CRITICAL TO THE NATION

A.
Energy Is Fundamentally Important

Congress has long recognized the importance of

abundant, reliable energy. The United States uses on

average over 20 million barrels of petroleum each day,

totaling 7.39 billion barrels each year.2 The energy it

provides enables virtually every aspect of American

life. It has also been key to the dynamism of the

American economy—the largest in the world—

enabling the rise of bedrock American industries such

as transportation, telecommunications, technology,

manufacturing, and finance.

Energy is likewise crucial to securing the future.

The U.S. Department of Defense relies extensively on

petroleum products.3 Nascent innovations, including

artificial intelligence and machine learning, have the

potential to transform society and similarly require

substantial energy resources. As Secretary of Energy

Chris Wright aptly observed regarding artificial

2 U.S. Energy Info. Admin., Frequently Asked Questions (FAQs):

How Much Oil Is Consumed in the United States? (updated Oct.

9, 2024), https://perma.cc/HX8T-H4LH.

3 U.S. Dep’t of Energy, Comprehensive Annual Energy Data:

Total Site-Delivered Energy Use in All End-Use Sectors, by

Federal Agency (Billion Btu), https://ctsedwweb.ee.doe.gov/

Annual/Report/TotalSiteDeliveredEnergyUseInAllEndUse

SectorsByFederalAgencyBillionBtu.aspx (visited Oct. 9, 2025).

7

intelligence, “We’re at the start of Manhattan Project

Two.… We could lose this race in many ways if we

don’t get energy right, we don’t unleash American

energy.”4

Just this year, Congress voted to increase oil and

gas production on federal land and the outer

continental shelf by raising the frequency of lease

sales and expanding areas available for resource

extraction. Pub. L. No. 119-21, §§ 50101–05, 139 Stat.

72, 137–44 (2025). Congress similarly expanded coal

mining on federal lands and expedited approval of

leases. Id. §§ 50201–04, 139 Stat. at 144–46; see also

42 U.S.C. § 15927(b)(1) (recognizing that “oil shale,

tar sands, and other unconventional fuels are

strategically important domestic resources that

should be developed to reduce the growing

dependence of the United States on politically and

economically unstable sources of foreign oil imports”).

These policies reflect the considered judgment of

Congress that such energy sources are vital to the

national interest and should be developed.

The Executive Branch similarly recognizes the

importance of abundant, reliable energy. The

President has placed energy at the forefront of his

priorities, even declaring a national energy

emergency to address strategic shortfalls. See

Declaring a National Energy Emergency, Exec. Order

No. 14156, § 1, 90 Fed. Reg. 8433, 8433–34 (Jan. 29,

2025). As the President explained, “We need a

reliable, diversified, and affordable supply of energy

4 Daniel Dassow, U.S. Energy Secretary, OpenAI Co-founder Say

AI Race Is ‘Manhattan Project 2’ In Oak Ridge Visit, Knoxville

News Sentinel (Feb. 28, 2025), https://perma.cc/P6MA-LUDT.

8

to drive our Nation’s manufacturing, transportation,

agriculture, and defense industries, and to sustain the

basics of modern life and military preparedness.” Id.

To that end, the President has issued Executive

Orders to streamline permitting processes, id. § 4, 90

Fed. Reg. at 8434–35; increase leases for oil and gas

production, including offshore leases, Unleashing

American Energy, Exec. Order No. 14154, 90 Fed.

Reg. 8353 (Jan. 29, 2025); establish a National Energy

Dominance Council, Establishing the National Energy

Dominance Council, Exec. Order No. 14213, 90 Fed.

Reg. 9945 (Feb. 20, 2025); direct resources to

strengthen and secure the national electricity grid,

Strengthening the Reliability and Security of the

United States Electric Grid, Exec. Order No. 14262, 90

Fed. Reg. 15521 (Apr. 14, 2025); and protect American

energy from state and local overreach, Protecting

American Energy from State Overreach, Exec. Order

No. 14260, 90 Fed. Reg. 15513 (Apr. 14, 2025).

Congress and the Executive Branch agree on the

unique necessity of abundant, reliable energy. Its

importance to the entire country cannot be overstated.

B.
State and Local Governments Are Trying

to Usurp Federal Authority

As the President has recognized, “American energy

suffers” when “State and local governments seek to

regulate energy beyond their constitutional or

statutory authorities.” Exec. Order No. 14260, 90 Fed.

Reg. at 15513. That is exactly what is happening here.

State and local governments, such as Respondents,

are supplanting the role assigned by the Constitution

to the federal government by using their state laws

and state courts to set national energy policy and

9

regulate interstate and international greenhouse-gas

emissions.

The Colorado Supreme Court insists that

Respondents are only “seek[ing] damages from

upstream producers for harms stemming from the

production and sale of fossil fuels,” and thus “do not

seek to regulate [greenhouse-gas] emissions.”

Pet.App.17a, 21a. That is wrong. Respondents openly

seek damages related to the effect of interstate and

international greenhouse-gas emissions on the global

climate.

This Court has been clear that “regulation can be

… effectively exerted through an award of damages.”

S.D. Building Trades Council v. Garmon, 359 U.S.

236, 247 (1959). Moreover, “[t]he obligation to pay

compensation can be, indeed is designed to be, a

potent method of governing conduct and controlling

policy.” Id.; see Kurns v. R.R. Friction Prods. Corp.,

565 U.S. 625, 637 (2012). This case is no exception. As

dissenting Justices Samour and Boatright astutely

concluded, “While Boulder’s state-law claims

masquerade as tort claims for damages, a closer look

at the substance of those claims’ allegations reveals

that Boulder seeks to effectively abate or regulate

interstate emissions.” Pet.App.32a (Samour, J., joined

by Boatright, J., dissenting).

The enormous damages alleged in cases like this

leave no doubt they will compel compliance with the

preferred energy policy of Respondents. Although

Respondents here declined to put a number on the

damages they seek, a similar case filed in Oregon

against similar defendants, including Petitioner

Exxon, requests more than $50 billion to abate the

10

alleged harms that a single county argues are the

result of increased global greenhouse-gas emissions.

Second Am. Compl. ¶ 552, County of Multnomah v.

Exxon Mobil Corp., No. 23-CV-25164 (Or. Cir. Ct.).

Dozens of analogous lawsuits remain pending across

the country, seeking similar damage awards.

When multiplied across these numerous actions,

which only continue to proliferate, the American

energy industry could be decimated. Even the threat

of such liability serves as a potent warning to any

company against maintaining—let alone increasing—

production.

Nor can Respondents disclaim the reach of their

claims. Their own complaint alleges harms from

alleged contributions by Petitioners to “alteration of

the climate,” see, e.g., Am. Compl. ¶¶ 1–2, 5–6, 62, 82,

Bd. of Cnty. Comm’rs of Boulder Cnty. v. Suncor

Energy (U.S.A.), Inc., No. 2018CV30349 (Colo. Dist.

Ct. June 11, 2018), which is a “global” effect, see id.

¶¶ 134, 137, 213. Respondents attribute these harms

to the worldwide oil and gas activities of Petitioners,

including operations in “the Canadian tar sands,” id.

¶¶ 384–88, 397; “Latin America,” id. ¶ 389; and

“Angola, Canada, Qatar, Russia and the United Arab

Emirates,” id. ¶ 94. Indeed, the Colorado Supreme

Court itself recognized that the case involves

“substantial issues of global import.” Pet.App.1a.

Other suits turn on similar claims that “[g]lobal

production and combustion of fossil fuels is the

central” cause of changes to the global climate, and

that the relevant defendants “have produced more

than 12% of the world’s fossil fuels since 1965, the

combustion of which has been the driving force

11

behind” the alleged harms. Am. Compl. ¶¶ 32, 319,

City of Hoboken v. Exxon Mobil Corp., No. HUD-L3179-20 (N.J. Super. Ct. Law Div. Apr. 21, 2023). As

Judge Stras has observed, despite attempts to

characterize such claims as traveling purely under

state law, referencing the pressing need to address

“climate change” more than 200 times in a complaint

reveals an actual intent to regulate an issue of

national and international consequence. See

Minnesota v. Am. Petroleum Inst., 63 F.4th 703, 717

(8th Cir. 2023) (Stras, J., concurring).

Indeed, the Intergovernmental Panel on Climate

Change (“IPCC”) has recognized that “[c]limate

litigation is an attempt to control, order or influence

the behaviour of others,” including at the “national

and international” level. 5 That is not the role of a

single State or locality. The Constitution places that

responsibility squarely with the federal government.

II.
THIS CASE IS STRAIGHTFORWARD

States lack authority to regulate pollution,

including greenhouse-gas emissions, originating

beyond their respective borders. That is the exclusive

domain of federal law. Congress did not change that

by passing the Clean Air Act.

A.
Interstate and International Emissions

Are the Domain of Federal Law

This Court has long held that disputes related to

interstate pollution are governed by federal law. In

5 IPCC,

Climate Change 2022: Mitigation of Climate Change,

Working Group III Contribution to the Sixth Assessment Report

of the Intergovernmental Panel on Climate Change 1375 (2022),

https://perma.cc/JS43-77KW.

12

Georgia v. Tennessee Copper Co., this Court

considered an original action by Georgia to enjoin

companies operating in Tennessee from “discharging

noxious gas” that drifted across the state border. 206

U.S. 230, 236 (1907). The Court explained that “by

their union,” States “made the forcible abatement of

outside nuisances impossible to each,” including

through operation of their state law and state courts.

Id. at 237. But they were not left without recourse.

The Constitution provided a new forum for such

disputes—a “suit in this Court,” governed by federal

common law. Id.

Since Georgia, “a mostly unbroken string of cases

has applied federal law to disputes involving

interstate air or water pollution.” City of New York,

993 F.3d at 91 (collecting cases). As the Tenth Circuit

explained:

Federal common law and not the varying

common law of the individual States is …

entitled and necessary to be recognized as a

basis for dealing in uniform standard with the

environmental rights of a State against

improper impairment by sources outside its

domain.

Texas v. Pankey, 441 F.2d 236, 241 (10th Cir. 1971).

This Court has repeatedly affirmed the inherently

federal nature of interstate pollution claims. In

Milwaukee I, this Court held that “federal common

law” governs claims related to “air and water in their

ambient or interstate aspects.” 406 U.S. at 103. This

Court noted the “overriding federal interest in the

need for a uniform rule of decision” and the “basic

interests of federalism” in a dispute over pollution in

13

Lake Michigan, which is “bounded … by four States.”

Id. at 105 n.6. The Court made clear in a follow-on

case that federal common law exists in such

circumstances because “state law cannot be used.”

City of Milwaukee v. Illinois (“Milwaukee II”), 451

U.S. 304, 313 & n.7 (1981) (emphasis added).

This Court surveyed its precedent and made

similar observations in International Paper Co. v.

Ouellette, highlighting that “regulation of interstate

water pollution is a matter of federal, not state, law.”

479 U.S. 481, 488 (1987); see id. (explaining that

Milwaukee I “held that these cases should be resolved

by reference to federal common law; the implicit

corollary of this ruling was that state common law was

preempted”).

And most recently, in AEP, this Court reiterated

that regulation of interstate emissions is

“undoubtedly” one of the areas where “the basic

scheme of the Constitution … demands” the

application of federal law. 564 U.S. at 421. Applying

state law “would be inappropriate.” Id. at 422.

Furthermore, if States lack authority to regulate

emissions originating in other States, they

undoubtedly cannot apply their law to emissions

originating in other countries. This Court has never

suggested that state law applies in the context of

international emissions. To the contrary, in

Milwaukee I, this Court emphasized the “overriding

federal interest in the need for a uniform rule of

decision” by relying on a case about exclusive federal

authority over an international matter. 406 U.S. at

105 n.6 (citing Banco Nacional de Cuba v. Sabbatino,

376 U.S. 398 (1964)). It would be passing strange if

14

state law somehow had greater purchase in an area

implicating the “exclusive authority” of the federal

government “in international relations and with

respect to foreign intercourse and trade.” Fuld v.

Palestine Liberation Org., 606 U.S. 1, 15 (2025)

(cleaned up); see also, e.g., Am. Ins. Ass’n v.

Garamendi, 539 U.S. 396, 419–20 (2003). Instead,

States have lacked authority to regulate interstate or

international emissions originating beyond their

borders.

B.
Congress Did Not Authorize States to

Regulate Interstate and International

Emissions in the Clean Air Act

Congress did not subtly transfer the exclusive

federal authority over interstate and international

emissions to the States when it passed the Clean Air

Act. The federalism canon does not allow such implied

reordering.

This Court has held that Congress must “enact

exceedingly clear language if it wishes to significantly

alter the balance between federal and state power.”

Cowpasture River Pres. Ass’n, 590 U.S. at 621–22

(emphasis added); see also, e.g., Gregory v. Ashcroft,

501 U.S. 452, 460 (1991) (“If Congress intends to alter

the usual constitutional balance between the States

and the Federal Government, it must make its

intention to do so unmistakably clear in the language

of the statute.” (cleaned up) (emphasis added)).

Congress provided no indication in the Clean Air Act,

much less an “exceedingly clear” one, that it intended

to alter this long-standing division between federal

and state authority in the context of interstate and

international emissions. Nor did the Colorado

15

Supreme Court identify clear language allowing the

application of state law to such disputes. That is the

end of the matter.

Congress similarly “does not alter the fundamental

details of a regulatory scheme in vague terms or

ancillary provisions—it does not, one might say, hide

elephants in mouseholes.” Am. Trucking Ass’ns, 531

U.S. at 468. Thus, Congress did not subtly empower

state law and state courts to pursue crippling

damages against an essential industry for worldwide

conduct, especially for claims within the exclusive

domain of federal law. That again is dispositive.

The Colorado Supreme Court also failed a basic

analysis of the Clean Air Act itself. That statute is a

comprehensive statutory and regulatory regime that

“displace[d]” the federal common law of interstate air

pollution. AEP, 564 U.S. at 424. Substituting one form

of federal regulation (the Clean Air Act) for another

(federal common law) does not imply any intent to

breathe life into state law claims. The text of the

Clean Air Act certainly does not expressly or impliedly

signal a new and expansive role for States to regulate

in areas from which they have been excluded. And it

would defy logic to say that the Clean Air Act prohibits

“federal judges” from “set[ting] limits on greenhouse

gas emissions” across the country, id. at 429

(emphasis added), while silently authorizing state

judges to do the same around the world.

The Colorado Supreme Court did not address these

basic principles of statutory interpretation. Instead, it

made a wrong turn at the start by applying a

presumption against preemption of state law.

Pet.App.11–12a. But as dissenting Justices Samour

16

and Boatright explained, that presumption does not

apply “[i]n a case like this one … where state law has

not traditionally occupied the field.” Pet.App.27a

(Samour, J., joined by Boatright, J., dissenting).

These dissenting justices share company with this

Court, which has been explicit that “in an area where

there has been a history of significant federal

presence,” the “‘assumption’ of nonpre-emption is not

triggered.” United States v. Locke, 529 U.S. 89, 108

(2000) (quoting Rice v. Santa Fe Elevator Corp., 331

U.S. 218, 230 (1947)). The field of interstate and

international pollution claims has always been

governed by federal law—first federal common law,

and now the Clean Air Act where applicable. Native

Vill. of Kivalina v. ExxonMobil Corp., 696 F.3d 849,

857 (9th Cir. 2012) (“If the federal common law cause

of action has been displaced by legislation, that means

that ‘the field has been made the subject of

comprehensive legislation’ by Congress.” (quoting

Milwaukee II, 451 U.S. at 314)). That leaves no room

for state law claims like those Respondents bring now.

C.
Confirming Federal Authority Over

Interstate and International Emissions

Respects States

Confirming federal authority over interstate and

international emissions would respect the sovereignty

and proper role of States. If each could regulate

emissions originating from the others, it would

undoubtedly “lead to chaotic confrontation” between

them. Int’l Paper Co., 479 U.S. at 496 (quoting Illinois

v. City of Milwaukee (“Milwaukee III”), 731 F.2d 403,

414 (7th Cir. 1984)).

17

Allowing States to reach beyond their respective

borders and set national energy policy is anathema to

the principles of horizontal federalism embodied in

the Constitution. “It follows from these principles,”

this Court has said, “that a State may not impose

economic sanctions” using its own laws “with the

intent of changing … lawful conduct in other States.”

BMW of N. Am., Inc. v. Gore, 517 U.S. 559, 572 (1996);

see Kansas v. Colorado, 206 U.S. 46, 95 (1907). Doing

so would undermine the “equal dignity and

sovereignty” of other States. Franchise Tax Bd. of Cal.

v. Hyatt, 587 U.S. 230, 245 (2019).

Federal

authority

over

interstate

and

international emissions is thus necessary to protect

the proper role and sovereignty of the States.

III.
FURTHER PERCOLATION IS UNNECESSARY

The question presented here is fully developed for

review. This Court now has the benefit of both a

majority opinion and dissent below; another state

supreme court decision, City & County of Honolulu v.

Sunoco LP, 537 P.3d 1173 (Haw. 2023); a decision by

the Second Circuit, see City of New York, 993 F.3d 81;

and analogous decisions by the Fourth and Seventh

Circuits, see North Carolina v. Tenn. Valley Auth., 615

F.3d 291 (2010); Milwaukee III, 731 F.2d 403. Further

percolation is cumulative, at best.

Moreover, the country simply cannot wait for this

issue to be decided at some indeterminate point in the

future. Dozens of these cases are underway in state

courts, and more will surely follow, emboldened by the

18

decision below.6 A similar case was filed earlier this

year by an individual alleging wrongful death based

6 See, e.g., California v. BP p.l.c., No. RG17875889 (Cal. Super.

Ct., Cnty. of Alameda); California v. BP p.l.c., No. CGC-17561370 (Cal. Super. Ct., Cnty. of S.F.); California v. Exxon Mobil

Corp., No. CGC-23-609134 (Cal. Super. Ct.); City of Imperial

Beach v. Chevron Corp., No. 17CV01227 (Cal. Super. Ct.); County

of Marin v. Chevron Corp., No. 17CV02586 (Cal. Super. Ct.);

County of San Mateo v. Chevron Corp., No. 17CV03222 (Cal.

Super. Ct.); City of Richmond v. Chevron Corp., No. 18CV00055

(Cal. Super. Ct.); City of Santa Cruz v. Chevron Corp.,

No. 17CV03243 (Cal. Super. Ct.); County of Santa Cruz v.

Chevron Corp., No. 17CV03242 (Cal. Super. Ct.); Connecticut v.

Exxon Mobil Corp., No. HHDCV206132568S (Conn. Super. Ct.);

Delaware v. BP Am. Inc., No. N20C-09-97 (Del. Super. Ct.);

District of Columbia v. Exxon Mobil Corp., No. 2020 CA 002892

B (D.C. Super. Ct.); Hawai‘i v. BP p.l.c., No. 1CCV-25-717 (Haw.

Cir. Ct.); City & County of Honolulu v. Sunoco LP, No. 1CCV-20380 (Haw. Cir. Ct.); County of Maui v. Sunoco LP, No. 2CCV-20283 (Haw. Cir. Ct.); City of Chicago v. BP p.l.c.,

No. 2024CH01024 (Ill. Cir. Ct.); Maine v. BP p.l.c., No. PORSCCV24-442 (Me. Super. Ct.); Massachusetts v. Exxon Mobil Corp.,

No. 1984CV03333 (Mass. Super. Ct.); Mayor & City Council of

Baltimore v. BP p.l.c., No. 24-C-18-4219 (Md. Cir. Ct.); Anne

Arundel County v. BP p.l.c., No. 02-CV-21-565 (Md. Cir. Ct.); City

of Annapolis v. BP p.l.c., No. 02-CV-21-250 (Md. Cir. Ct.);

Minnesota v. Am. Petroleum Inst., No. 62-CV-20-3837 (Minn.

Dist. Ct.); Platkin v. Exxon Mobil Corp., No. MER-L-1797-22

(N.J. Super. Ct. Law Div.); City of Hoboken, No. HUD-L-3179-20;

City of New York v. Exxon Mobil Corp., No. 451071/2021 (N.Y.

Sup. Ct.); City of New York v. BP p.l.c., No. 18-cv-182 (S.D.N.Y.);

Town of Carrboro v. Duke Energy Corp., No. 24CV3385-670 (N.C.

Super. Ct.); County of Multnomah, No. 23-CV-25164; Bucks

County v. BP p.l.c., No. 2024-1836 (Pa. C.P.); Rhode Island v.

Chevron Corp., C.A. No. PC-2018-4716 (R.I. Super. Ct.); Vermont

v. Exxon Mobil Corp., No. 21-CV-02778 (Vt. Super. Ct.); King

County v. BP p.l.c., No. 18-2-11859-0 (Wash. Super. Ct.); Makah

Indian Tribe v. Exxon Mobil Corp., No. 23-2-25216-1 (Wash.

Super. Ct.); Shoalwater Bay Indian Tribe v. Exxon Mobil Corp.,

19

on a heat wave. See Leon v. Exxon Mobil Corp., No. 252-15986-8 (Wash. Super. Ct.). And certain legal

academics are now advocating for prosecutors to bring

“climate homicide” charges and exercise civil

forfeiture to seize company assets, restructuring them

into public benefit corporations. David Arkush &

Donald Braman, Climate Homicide: Prosecuting Big

Oil for Climate Deaths, 48 Harv. Env’t L. Rev. 45

(2024).

These issues have also created significant friction

between the States. Cf. supra Part II.C. Nearly half

the country was recently before this Court asking for

review of the issue in this case, explaining their sister

States “threaten not only our system of federalism and

equal sovereignty among States, but our basic way of

life.” Mot. at 2, Alabama v. California, 145 S. Ct. 757

(2025) (No. 22O158). An even larger coalition of States

has now filed suit against New York and intervened

in a suit against Vermont to enjoin their “climate

superfund” laws that impose decades of retroactive

liability on American energy companies for their

alleged role in global greenhouse-gas emissions, as

well. West Virginia v. James, No. 1:25-cv-168

(N.D.N.Y.); Chamber of Com. of the U.S. of Am. v.

Moore, No. 2:24-cv-1513 (D. Vt.).

The situation has become so fraught that the U.S.

Department of Justice has sought to enjoin Hawaii

and Michigan from filing their own lawsuits, see

United States v. Michigan, No. 1:25-cv-496 (W.D.

Mich.); United States v. Hawaii, No. 1:25-cv-179 (D.

No. 23-2-25215-2 (Wash. Super. Ct.); Municipality of Bayamón v.

Exxon Mobil Corp., No. 3:22-cv-1550 (D.P.R.); Municipality of

San Juan v. Exxon Mobil Corp., No. 3:23-cv-1608 (D.P.R.).

20

Haw.); and New York and Vermont from

implementing their “climate superfund” laws, United

States v. New York, No. 1:25-cv-3656 (S.D.N.Y.);

United States v. Vermont, No. 2:25-cv-463 (D. Vt.).

This case, and others like it, threaten the

abundant, reliable energy that underpins every aspect

of American life, including the standard of living for

ordinary Americans. Although national energy policy

is the subject of vigorous debate, it is a national issue

that must be decided at the national level—by officials

elected by the people of all States—not in a local jury

room. The federal government must be permitted to

fulfill its role in setting national energy policy and

regulating interstate and international emissions.

This Court should put an end to these

unconstitutional attempts to dictate national energy

policy from state courthouses before more, and

irreparable, damage is done.

21

CONCLUSION

The petition for certiorari should be granted.

Respectfully submitted,

October 9, 2025

MICHAEL BUSCHBACHER

JARED M. KELSON

Counsel of Record

JENNIFER K. HARDY

LAURA B. RUPPALT

BOYDEN GRAY PLLC

800 Connecticut Avenue NW

Suite 900

Washington, DC 20006

(202) 955-0620

jkelson@boydengray.com